In general, a textile product such as a dyed denim fabric has been decolorized to create a used and abused appearance in the dyed cotton fabric such as denim fabric. FIG. 1 is a flow chart of a fabric decolorization method in the related art. The fabric decolorization method includes a series of dry processes and a subsequent series of wet processes.
Dry Processes:
The dry processes include the following first to third steps, Step C1, Step C2, and Step C3. In Step C1, a hand shaving whisker process is carried out by shaving in hand the dyed cotton fabric such as denim fabric and/or whiskering in hand the dyed cotton fabric such as denim fabric. In Step C2, a hand-sand process is carried out by rubbing in hand a sand-paper on the cotton fabric such as denim fabric. The initial two processes, the hand shaving whisker process in Step C1 and the hand-sand process in Step 2, are carried out to create a vintage look of the dyed cotton fabric such as denim fabric. In Step C3, a potassium permanganate solution is sprayed to fade out the dyed color of indigo, for example, of the cotton fabric such as denim fabric. This process for spraying the potassium permanganate solution in Step C3 is carried out to make whiten the dyed cotton fabric such as denim fabric in addition to the initial two processes, the hand shaving whisker process in Step C1 and the hand-sand process in Step 2.
The dry processes are time-consuming and costly processes since the dry processes are carried out in hand or manually. For a piece of dyed cotton fabric such as denim fabric, each of the hand shaving whisker process in Step C1 and the hand-sand process in Step 2 will take about 10 min. and the potassium permanganate solution spraying process in Step C3 will take about 2 min. The hand shaving process in Step C1 will allow 15,000 pieces of dyed cotton fabric such as denim fabric to be treated manually by 140 people per day. The hand whisker process in Step C1 will allow 15,000 pieces of dyed cotton fabric such as denim fabric to be treated manually by 60 people per day. The potassium permanganate solution spraying process in Step C3 will allow 15,000 pieces of dyed cotton fabric such as denim fabric to be treated manually by 80 people per day. In total, the dry processes will take 3 days with 280 people to manually treating 15,000 pieces of dyed cotton fabric such as denim fabric. Thus, the estimation of the cost for the dry processes will be about 1.5 US Dollars per a piece of dyed cotton fabric such as denim fabric.
Wet Process:
The wet process includes the following fourth to eleventh steps, Step C4 through Step C11, subsequent to the above-described first to third steps, Step C1 to Step C3. In Step C4, a desizing process as a pre-washing process is carried out using a detergent and a desizing agent at a temperature of, for example, but not limited to, 60° C. for about 20 min. for removal of the Size material such as starch from the sized cotton fabric such as denim fabric. The desizing process is carried out to facilitate penetration, into the sized cotton fabric such as denim fabric, of chemicals and dyes applied during subsequent washing processes for fading the dyed color of the cotton fabric. In case of a cotton fabric of a weight of 60 kg, the desizing process is carried out using 600 liters of water and then a rinsing process is carried out using 600 liters of water. In total, 1200 liters of water need to be used for desizing process at 60 kg garment weight in Step C4.
In Step C5, a combined-stone-enzyme-washing process for washing the desized cotton fabric is carried out at a temperature in the range of 30-45° C., for example, but not limited to, preferably about 40° C. for about 35 min. using pumice stones in the presence of an enzyme such as an acid enzyme with 600 liters of water to modify the appearance, to impart worn-out look and to improve the comfort ability of the cotton fabric, especially denim fabric. Enzyme washing of the desized denim fabric helps in bio-polishing and to fade as a whole the dyed color of the designed cotton fabric such as denim fabric to a desired degree depending on the processing time and conditions. Adding pumice stone with the enzyme will extend the degree of fading and add special effect in the multi ply areas like different seams and hems. The combined stone enzyme washing process is carried out using 600 liters of water and then a rinsing process is carried out using 600 liters of water. In total, 1200 liters of water need to be used for color-fading process at 60 kg garment weight in Step C5.
In Step C6, a dry process for drying the washed cotton fabric is carried out in a dry air at a temperature in the range of 60-85° C., for example, but not limited to, preferably about 85° C. for about 45 min.
In Step C7, in order to achieve better hand-feeling of the garment, a chemical treatment process for dipping the dried cotton fabric into chemicals is carried out for about 45 min, as a wrinkle free finishing that is widely used to impart wrinkle-resistance to cotton fabrics. Crosslinking agent, catalyst, additives, and surfactants are used. It has been known that crosslinking agents will change woven and knitted fabrics composed of cellulosic fibers and their blends with synthetic fibers in such a way that the resulting textiles are easier to care for. It allows the reaction to be carried out within the 130-180° C. temperature range usually employed in the textile industry, and within the usual curing times. Three classes of catalysts are distinguished in the dry crosslinking process commonly used such as ammonium salts, e. g. ammonium chloride, sulfate and nitrate; metal salts, e. g. magnesium chloride, zinc nitrate, zinc chloride, aluminum sulfate and aluminum hydroxyl-chloride; and catalyst mixtures, e. g. magnesium chloride with added organic and inorganic acids or acid donors. The additives is to offset partly or completely the adverse effects of the crosslinking agent. Typical examples of the additives may include, but are not limited to, polymers based on acrylic monomers, vinyl monomers, siloxanes, amides, urethanes and ethylene; low-molecular substances such as fatty acid derivatives and quaternary ammonium compounds; and mixtures of these substances. Surface-active substances are necessary to ensure that the fabric is wet rapidly and thoroughly during padding and to stabilize the recipe components and liquors.
In Step C8, a neutralization process is carried out for about 8 min. by using 600 liters of water and then a rinsing process is carried out using 600 liters of water. In total, 1200 liters of water need to be used for the neutralization process at 60 kg garment weight in Step C8.
In Step C9, a chemical removing process as a clean-up process for removing from the cotton fabric the chemicals used in Step C7 is carried out for about 10 min. by using 600 liters of water and then a rinsing process is carried out using 600 liters of water. In total, 1200 liters of water need to be used for the chemical removing process at 60 kg garment weight in Step C9.
In Step C10, an enzyme treatment process for fading color of the cotton fabric with worn and aged effects is carried out for about 20 min. by using 600 liters of water and then a rinsing process is carried out using 600 liters of water. In total, 1200 liters of water need to be used for the enzyme treatment process at 60 kg garment weight in Step C10.
In Step C11, to make a hand-feel soft of the cotton fabric, a softening process for softening the color-fade cotton fabric with any available softener is carried out for about 5 min, by using 600 liters of water and then a rinsing process is carried out using 600 liters of water. In total, 600 liters of water need to be used for the softening process at 60 kg garment weight in Step C11.
Water Consumption:
In total, 7200 liters of water need to be used in the wet process for decolorization from Steps C4 to C11 at 60 kg garment weight for 30 pieces of cotton fabric, and total operating time is 188 min. for 30 pieces of cotton fabric.
Cost:
For 30,000 pieces of cotton fabric, 10 machines are used for 33.3 days. The estimated cost for the wet process is about 1.5 US Dollars for each piece of cotton fabric. The estimated total cost for the dry process and the wet process is about 3.0 US Dollars for each piece of cotton fabric.